WIP: feat(yaml): introduce multiple streams and pressures functionality in process_systems and process_simulations by olelod · Pull Request #1453 · equinor/ecalc

olelod · 2026-03-23T12:09:37Z

Summary

Refactors the process system and simulation YAML types to support interstage topology — enabling expression of legacy multi-stream and multi-pressure compressor trains in the new YAML format.

All types live in yaml_process_system.py.

Process system topology (`PROCESS_SYSTEMS`)

Type	Description
`COMPRESSOR_STAGE`	Single compressor stage with inlet temperature
`PRESSURE_DROP`	Interstage pressure drop element
`MIXER`	Stream injection point (one per injected stream)
`SPLITTER`	Stream extraction point (one per extracted stream)
`SERIAL`	Ordered list of item references; carries `ANTI_SURGE` (default: `INDIVIDUAL_ASV`)

PRESSURE_DROP, MIXER, and SPLITTER are new interstage topology types.

Process simulation (`PROCESS_SIMULATIONS`)

Each simulation has a list of TARGETS (one = serial, many = parallel — implicit from count) and a required STREAM_DISTRIBUTION (COMMON_STREAM or INDIVIDUAL_STREAMS, both accept stream refs or inline stream definitions).

Each target carries:

TARGET: reference to a SERIAL process system
CONSTRAINTS: map of item name / train name → OUTLET_PRESSURE + PRESSURE_CONTROL
MIXER_STREAMS: map of mixer name → inlet stream
SPLITTER_RATES: map of splitter name → extraction rate

Parse-time validation

Simulation targets must reference a known SERIAL process system
Every train must have an outlet constraint keyed by the train name
Every MIXER in a train must have a MIXER_STREAMS entry per target
Every SPLITTER in a train must have a SPLITTER_RATES entry per target
Constraint keys must be valid item names or the train name
Constraints must appear in topological order (matching SERIAL.items)
UPSTREAM_CHOKE only valid on the first constraint in topological order
DOWNSTREAM_CHOKE only valid on the last constraint in topological order
INDIVIDUAL_STREAMS: inlet stream count must match target count
COMMON_STREAM: each RATE_FRACTIONS list must have one entry per target
SERIAL.items must not reference another SERIAL (no nested serial trains)
MIXER_STREAMS keys must reference MIXER items in the train
SPLITTER_RATES keys must reference SPLITTER items in the train
COMMON_STREAM overflow FROM/TO references must be valid target names

Mapper

process_simulation_mapper.py updated to resolve string item references via reference_service, read pressure control from per-target outlet constraints, and read anti-surge from train.anti_surge. Multi-segment trains (more than one constraint) raise NotImplementedError pending MultiPressureSolver support.

Example YAML

INLET_STREAMS:
  feed_stream:
    FLUID_MODEL: dry_gas
    RATE:
      VALUE: SIM1;FEED_RATE
      UNIT: SM3_PER_DAY
  injection_stream:
    FLUID_MODEL: wet_gas
    RATE:
      VALUE: SIM1;INJECTION_RATE
      UNIT: SM3_PER_DAY
  train_a_stream:
    FLUID_MODEL: dry_gas
    RATE:
      VALUE: SIM1;TRAIN_A_RATE
      UNIT: SM3_PER_DAY
  train_b_stream:
    FLUID_MODEL: dry_gas
    RATE:
      VALUE: SIM1;TRAIN_B_RATE
      UNIT: SM3_PER_DAY

PROCESS_SYSTEMS:
  - TYPE: COMPRESSOR_STAGE
    NAME: stage_1
    INLET_TEMPERATURE: 30
    COMPRESSOR: my_compressor

  - TYPE: PRESSURE_DROP
    NAME: interstage_choke
    PRESSURE_DROP: 3

  - TYPE: MIXER
    NAME: injection_point

  - TYPE: COMPRESSOR_STAGE
    NAME: stage_2
    INLET_TEMPERATURE: 40
    COMPRESSOR: my_compressor

  - TYPE: SERIAL
    NAME: main_train
    ANTI_SURGE: INDIVIDUAL_ASV
    ITEMS:
      - stage_1
      - interstage_choke
      - injection_point
      - stage_2

  - TYPE: COMPRESSOR_STAGE
    NAME: train_a_stage
    INLET_TEMPERATURE: 30
    COMPRESSOR: my_compressor

  - TYPE: SERIAL
    NAME: train_a
    ANTI_SURGE: COMMON_ASV
    ITEMS:
      - train_a_stage

  - TYPE: COMPRESSOR_STAGE
    NAME: train_b_stage
    INLET_TEMPERATURE: 30
    COMPRESSOR: my_compressor

  - TYPE: SERIAL
    NAME: train_b
    ANTI_SURGE: INDIVIDUAL_ASV
    ITEMS:
      - train_b_stage

PROCESS_SIMULATIONS:
  # Serial train with interstage mixer and pressure drop
  - NAME: sim_serial
    TARGETS:
      - TARGET: main_train
        MIXER_STREAMS:
          injection_point: injection_stream
        CONSTRAINTS:
          injection_point:
            OUTLET_PRESSURE: 50
            PRESSURE_CONTROL: DOWNSTREAM_CHOKE
          main_train:
            OUTLET_PRESSURE: 120
            PRESSURE_CONTROL: DOWNSTREAM_CHOKE
    STREAM_DISTRIBUTION:
      METHOD: INDIVIDUAL_STREAMS
      INLET_STREAMS:
        - feed_stream

  # Parallel trains with individual streams
  - NAME: sim_parallel_individual
    TARGETS:
      - TARGET: train_a
        CONSTRAINTS:
          train_a:
            OUTLET_PRESSURE: 120
            PRESSURE_CONTROL: COMMON_ASV
      - TARGET: train_b
        CONSTRAINTS:
          train_b:
            OUTLET_PRESSURE: 120
            PRESSURE_CONTROL: DOWNSTREAM_CHOKE
    STREAM_DISTRIBUTION:
      METHOD: INDIVIDUAL_STREAMS
      INLET_STREAMS:
        - train_a_stream
        - train_b_stream

  # Parallel trains with common stream distribution
  - NAME: sim_parallel_common
    TARGETS:
      - TARGET: train_a
        CONSTRAINTS:
          train_a:
            OUTLET_PRESSURE: 120
            PRESSURE_CONTROL: COMMON_ASV
      - TARGET: train_b
        CONSTRAINTS:
          train_b:
            OUTLET_PRESSURE: 120
            PRESSURE_CONTROL: DOWNSTREAM_CHOKE
    STREAM_DISTRIBUTION:
      METHOD: COMMON_STREAM
      INLET_STREAM: feed_stream
      SETTINGS:
        - RATE_FRACTIONS: [0.6, 0.4]
          OVERFLOW:
            - FROM_REFERENCE: train_a
              TO_REFERENCE: train_b
        - RATE_FRACTIONS: [0.5, 0.5]

jsolaas · 2026-03-25T07:57:43Z

+class YamlInterstageProcessSystem(YamlBase):
+    type: Literal["INTERSTAGE"]
+    name: ProcessSystemReference
+    items: list[YamlInterstageItem] = Field(
+        default_factory=list,
+        title="ITEMS",
+        description="Ordered list of choke, mixer, and splitter units at this interstage location.",
+    )


Do we actually need this? Can we instead just have a list of units in addition to CompressorStages when setting up the train?

jsolaas · 2026-03-25T07:58:35Z

    type: Literal["SERIAL"]
    name: ProcessSystemReference
-    items: list[YamlItem[YamlCompressorStageProcessSystem]]
+    items: list[YamlItem[YamlCompressorStageProcessSystem | YamlInterstageProcessSystem]]


Suggested change

items: list[YamlItem[YamlCompressorStageProcessSystem | YamlInterstageProcessSystem]]

items: list[YamlItem[YamlCompressorStageProcessSystem | YamlInterstageChoke | YamlInterstageSplitter | YamlInterstageMixer]]

jsolaas · 2026-03-25T07:59:42Z


 class YamlProcessConstraints(YamlBase):
-    outlet_pressure: YamlExpressionType | None = Field(
+    discharge_pressure: YamlExpressionType | None = Field(


Should we use discharge instead of inlet? inlet/outlet seems to work for streams, is it different for pressure?

jsolaas · 2026-03-25T08:07:47Z

+        title="DISCHARGE_PRESSURE",
+        description="Target discharge pressure [bara].",
+    )
+    pressure_control: YamlPressureControl | None = Field(


Will constraint, anti-surge and pressure control always go hand-in-hand?

I think we also should consider introducing a type for constraint, maybe switch to a list. That gives us more flexibility in case we need to introduce different constraints.

If combining constraint and 'how to solve' like this we should also consider a different name than constraint

frodehk · 2026-04-08T14:18:06Z

@@ -231,12 +231,12 @@ def _get_compressor(self, yaml_compressor_stage: YamlCompressorStageProcessSyste
        )

    def _get_compressors(self, target: YamlSerialProcessSystem, shaft: Shaft) -> list[Compressor]:


Suggestion - replace _get_compressors() and _get_compressor() with:

_map_stage_to_process_units() -> list[ProcessUnit] (Compressor and TemperatureSetter)

_map_pressure_drop_to_process_units() -> list[ProcessUnit] (Choke)

_get_process_units() -> list[ProcessUnit] (Choke, TemperatureSetter, Compressor)

Will be added in a follow up PR involving yaml-to-domain mapping

Consolidate all process system types in yaml_process_system.py. - Add interstage topology types: PRESSURE_DROP, MIXER, SPLITTER - Add SERIAL anti-surge config (INDIVIDUAL_ASV / COMMON_ASV) - Restructure simulation targets with per-item constraints carrying OUTLET_PRESSURE and PRESSURE_CONTROL - Add MIXER_STREAMS and SPLITTER_RATES to simulation targets - Add parse-time validators in YamlAsset (topological ordering, choke placement, reference consistency)

olelod force-pushed the feat/yaml-interstage-types branch from 2f01beb to 507f040 Compare March 23, 2026 12:18

jsolaas reviewed Mar 25, 2026

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olelod force-pushed the feat/yaml-interstage-types branch 4 times, most recently from 08d553e to 88e14e6 Compare April 8, 2026 11:20

olelod changed the title ~~WIP: feat(yaml): introduce INTERSTAGE process system type and PRESSURE_CON…~~ WIP: feat(yaml): introduce multiple streams and pressures functionality in process_systems and process_simulations Apr 8, 2026

olelod force-pushed the feat/yaml-interstage-types branch 5 times, most recently from 8e95998 to fbae582 Compare April 8, 2026 12:09

frodehk reviewed Apr 8, 2026

View reviewed changes

olelod force-pushed the feat/yaml-interstage-types branch from fbae582 to 4289e42 Compare April 14, 2026 17:25

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WIP: feat(yaml): introduce multiple streams and pressures functionality in process_systems and process_simulations#1453

WIP: feat(yaml): introduce multiple streams and pressures functionality in process_systems and process_simulations#1453
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olelod commented Mar 23, 2026 •

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	items: list[YamlItem[YamlCompressorStageProcessSystem \| YamlInterstageProcessSystem]]
	items: list[YamlItem[YamlCompressorStageProcessSystem \| YamlInterstageChoke \| YamlInterstageSplitter \| YamlInterstageMixer]]

		@@ -231,12 +231,12 @@ def _get_compressor(self, yaml_compressor_stage: YamlCompressorStageProcessSyste
		)

		def _get_compressors(self, target: YamlSerialProcessSystem, shaft: Shaft) -> list[Compressor]:

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olelod commented Mar 23, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Process system topology (PROCESS_SYSTEMS)

Process simulation (PROCESS_SIMULATIONS)

Parse-time validation

Mapper

Example YAML

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frodehk Apr 8, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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olelod commented Mar 23, 2026 •

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Process system topology (`PROCESS_SYSTEMS`)

Process simulation (`PROCESS_SIMULATIONS`)

frodehk Apr 8, 2026 •

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